1. Field of the Invention
The present invention relates to a zoom lens system having a diffractive optical element suitable for a film camera, a video camera, and a digital still camera.
2. Related Background Art
With the advance of technology, various types of zoom lens system have been proposed. As an optical system for a film camera, a video camera, and a digital still camera in particular, a three-group type zoom lens system, which is called a telephoto type, having a construction of, in order from an object, a positive-negative-positive power arrangement with a short back focal length. For such example, there is Japanese Paten Application Laid-Open No. 11-305126.
However, it has been very difficult to satisfy both high optical performance (in particular, color drift) and compactness with a simple mechanism in accordance with recent progress in imaging technology such as miniaturizing the pixel pitch of an imaging device.